2010-02-22

Tutorial: Photoshop Image Stacking for Day Trails

Creating star trails is a well known technique in Astrophotography and the same technique can be used to create trails of activity during the day. The results are both unique and potentially useful to identify heavily used routes or flows in urban areas.

The concept is simple, set up your camera, webcam or iphone at a suitable location, and capture an image at regular intervals, for our example we captured an image every 2 seconds pointing down at a London street:

We left the camera running for an hour capturing 1800 images, saved into a folder on our computer.

The next step is to open photoshop and start stacking the images.

Image Stacking in Photoshop

The images will be stacked onto of an intially blank image via a simple automated action:

1) Create a new blank black image the same size are your captured photographs.

2) Load the action into the action windows in Photoshop and load the action Startrails.atn.

3) In Photoshop click 'File', 'Automate' and 'Batch'. Select the action you have just loaded and choose your directory with the images as source and make sure you select 'None' for the output directory.

Click 'Ok' and leave it running, our Mac laptop took around an hour to stack the images - resulting in the 'Day Trail' below:

You can clearly see the path of the traffic and the most utilised sections of the walkways over the hour, we simply like the effect.

2 comments:

HI ! Thanks for that explanation, it's been some days I was looking for something like that. But the problem is, I'm French, my photoshop is in French and I'm brand new to photoshop... and I can't manage to make it work...I made like 20 shots with my iphone to give it a try, made a new image in Photoshop at the same size of the pictures, downloaded the Startrails.atn action, loaded it into photoshop as you screen shot shows, but when I go to what's supposed to be in French "File" / "Automate" then "Batch", the action is named "Set1" (I thought it'd be named "Startrails"...). I select the folder where the pics are, then hit done, it seems something is working in the background, then the new blank image in Photoshop appears and nothing else... not the photos... quite nothing... So I suppose I do something wrong and I can't manage to know what. Could you help me with that ?